Die Küste, 81 (2014), 273-290 
285 
HBM works with discharge calculations from water level measurements in Neu Darchau 
which lies outside die EL-model region. Because the calculated river discharges of more 
than 4000 m 3 /s, which were nearly five times as high as the medium discharge, never 
occurred before, also diese values were fraught widi uncertainty. 
Zollenspieker Geesthacht 
Figure 12: Water levels during Elbe flood at Figure 13: Water levels during Elbe flood at 
station Zollenspieker. station Geesthacht-UP. Additionally model 
results at station Geesthacht-OP are shown. 
In spite of tiiese uncertainties BSH-HBM captured the Elbe flood very well at most sta 
tions between St.Pauli and Geesthacht like for example Zollenspieker (Fig. 12). Only 
directiy below the weir in Geesthacht (“Unterpegel” - UP) the absolute peak was mod 
elled about 0.5 m to low. Elowever this could be explained with difficulties in modelling 
the weir itself, because during die flood the weir was completely opened and directiy 
above die weir (“Oberpegel” — OP) die modelled water level matched very good to die 
observations (Fig. 13). 
4.2 Cyclone Xaver at 5th and 6th December 2013 
At 5 th and 6 th December 2013 the cyclone Xaver reached die inner German Bight with 
very high middle wind speeds between 45 and 55 knots (9-10 Beaufort) from north 
westerly directions (Fig. 15). Because of these high middle winds and gales up to 12 Beau 
fort over almost the whole two days, up to four storm surges and up to two strong storm 
surges in a row could be observed at almost all German North Sea stations. The highest 
water level elevation during Xaver could be observed at station St.Pauli with a deviation 
of 3.98 m above die mean high water, which means a water level of 6.09 m above mean 
sea level — a very strong storm surge and the second highest observed value ever. 
Even if die low waters were overestimated by BSF1-F1BM during Xaver, the model 
turned out to be a very useful tool for die scientists of die storm surge forecasting center 
because die storm surges were captured very well. At station Cuxhaven die errors of the 
maximum water levels during high waters were below 10 cm and at station St.Pauli they 
were below 25 cm (Fig. 14), which is a very good result taking die extraordinary high ob 
served values into account.